Philosophy is a systematic study of general and fundamental questions concerning topics like existence, reason, knowledge, value, mind, and language. It is a rational and critical inquiry that reflects on its own methods and assumptions.
Physics was originally part of philosophy, like Isaac Newton's observation of how gravity affects falling apples.
Aristotle was a major figure in ancient philosophy and developed a comprehensive system of thought including metaphysics, logic, ethics, politics, and natural science.
Portrait of Avicenna on a silver vase. He was one of the most influential philosophers of the Islamic Golden Age.
Knowledge is an awareness of facts, a familiarity with individuals and situations, or a practical skill. Knowledge of facts, also called propositional knowledge, is often characterized as true belief that is distinct from opinion or guesswork by virtue of justification. While there is wide agreement among philosophers that propositional knowledge is a form of true belief, many controversies focus on justification. This includes questions like how to understand justification, whether it is needed at all, and whether something else besides it is needed. These controversies intensified in the latter half of the 20th century due to a series of thought experiments called Gettier cases that provoked alternative definitions.
The owl of Athena, a symbol of knowledge in the Western world
Declarative knowledge can be stored in books.
Knowing how to ride a bicycle is one form of non-propositional knowledge.
Perception relies on the senses to acquire knowledge.